1. Field of the Invention
The present invention relates to a method of manufacturing various kinds of elongate ceramic articles, such as ceramic filters, ceramic heaters, ceramic furnace tools, electrode supporting elements, etc.
2. Description of the Related Art
Recently, in manufacturing ceramic elongate articles such as, for example, cylindrical ceramic filters, cylindrical ceramic heaters, ceramic furnace tools, and electrode supporting elements, there has been an increased demand to improve a performance of each ceramic article by enlarging the filtering area, heating area, power generating area, etc. of each article. To meet such a demand, it is of course necessary to make the articles more longer.
Generally, ceramic articles are required to have a high straightness. Therefore, it has been a conventional practice to hang an upper end portion of an elongate ceramic shaped-body on a supporting device and suspend the shaped-body for subjecting it to a firing.
However, when using a ceramic raw material with a large specific gravity, tensile stresses due to the dead weight of the shaped body becomes larger as the shaped-body is made longer, causing not only cracks or fractures in the shaped-body, but also significant differences in dimension and performance (for example, difference in porosity) between the upper end portion and the lower end portion of the shaped-body.
On the other hand, a manufacturing method is known in which a ceramic shaped-body is placed on a table and subjected to a firing in an attitude in which the longitudinal direction of the shaped-body is oriented in a horizontal direction. An elongate ceramic body is obtained after the firing, and is processed into a predetermined dimension. However, the method provides the article with a substantial deflection after the firing, and making it very difficult to subject the article to a high-precision-processing, thereby increasing the manufacturing cost.